Wind turbines are installations with a very tall tower which typically carries a rotor, housing and an electric generator of the wind turbine on its top. Since the used towers are very large in height in order to enable the use of a rotor with a large radius or length of the rotor blades the wind turbines are very heavy. Additionally the wind turbines are of course typically installed in topographic areas in which a strong wind is quite common and therefore the construction of the wind turbines have to be that strong to withstand the forces acting on such turbines due to the strong wind with typically high wind speed.
Therefore strong foundations are necessary requirements of the construction of such wind turbines.
Such foundations are well known in the art. The article BONUS Wind Turbines, Foundations, Foundation, Bonus Wind turbines, rev. 3 pages 1 to 4, 21.03.02 discloses a gravity foundation with a concrete base plate with a central concrete plinth. Furthermore it discloses piled foundations with pre-fabricated piles which will be hammered to the necessary depth into the ground and foundations with piles which will be cast in situ.
The prior art document EP 1058787 B1 discloses a foundation which is assembled of essentially uniformly formed base piece segments which are made of steel and which are arranged such that the assembled piece segments create a circular steel foundation with a hole at the center of the circle.
On-shore foundations are usually created at the location of the wind turbine installation using standard concrete casting technology to cast the foundation in situ. The above mentioned document EP 1058787 B1 discloses an off-shore foundation which is not used on-shore.
The above mentioned foundations show the disadvantage that the concrete foundations are difficult to produce at the location of the wind turbine installation and that the steel foundation is not well suited for heavy on-shore wind turbine installations.